It was probably because I was deep in thought after the meeting that I didn’t think hard enough about the message waiting for me on my desk. It was short and clear, and read: A man telephoned. He said he was a friend of Ahmed. He will wait for you at the farthest table at the back of the downstairs floor of Richoux in Knightsbridge until three o’clock.

I grilled the girl who had taken the message, but she could give me very little help. The voice was foreign, unsteady, and the caller obviously had a limited vocabulary. I could have had the voice played back, as all incoming telephone calls are automatically taped, but there wasn’t enough time to go winding backwards and forwards through the tape, and since I didn’t know anyone who didn’t speak English fluently, hearing the voice probably wouldn’t have helped me. I put my jacket and coat on and went out through the front entrance of number forty-six into Carlton House Terrace.

It was a bitterly cold day, sleeting slightly. I did up my coat buttons, put my hands in my pockets, and started to walk down towards Pall Mall to find a taxi. I was surprised to hear the familiar diesel rattle after only a few moments, and turned around, to see a taxi with its ‘For Hire’ light on, coming down right behind me. I flagged it down and climbed in. ‘Harrods,’ I said, Richoux being right across the road from the department store, which would give me a chance to see if there was anyone hanging around watching Richoux who shouldn’t have been.

‘Pardon?’ he said in a thick accent. He was young – couldn’t have been much more than twenty-two – with a Middle-Eastern complexion, and a large gold-coloured watch.

‘Harrods,’ I repeated.

‘Harrods, Knightsbridge?’ he asked.

‘Correct.’ During the best part of thirty-two years living in London, I had never come across more than one Harrods. This man obviously knew better. The watch was a genuine Rolex. I wondered at which branch of Harrods he’d bought it. The cab was smart – almost brand new; maybe it came from Harrods too. I leaned forward to the partition window. ‘Nice new cab,’ I said.

‘Yes,’ he laughed nervously, ‘yes, this is my cab.’